Maryland resident Carol Porter had a neuroendocrine tumor and had no idea until she went to see a gastrointestinal doctor for acid reflux.

"There were no symptoms before, during and after," Porter told 11 News. "I had a colonoscopy and endoscopy. They found a little tumor on my stomach, and that's what it turned out to be."

Mercy Medical Center oncologist Dr. Sandy Kotiah said neuroendocrine tumors are rare. They develop from hormonal cells, but scientists don't really know why. She said it can be a difficult cancer for doctors to diagnose if they don't know what they're looking for.

"It's mainly found in the small bowel, and what happens is a lot of people have very vague symptoms for many, many years -- dry flushing, diarrhea, wheezing. They'll go to their doctor and be diagnosed with irritable bowel syndrome or something else, and it'll take about five to seven years before they get diagnosed correctly," Kotiah explained.

Other symptoms include abdominal pain and cramping; reddish spots or veins, which are often on the face, chest and arms; bluish spots on the skin; heart palpitations; weight gain or loss; unstable blood pressure and unstable blood sugar.

If it's caught early, like in Porter's case, the treatment of choice is surgery. She had a small portion of her stomach removed and her prognosis is very good.

Kotiah said there's a lot of research going on regarding the issue, and treatments for neuroendocrine tumors are improving all the time.